Apparatus for water sampling

ABSTRACT

The invention relates to an apparatus for water sampling. The invention relates to such a water sampling apparatus that permits intake of so-called composite samples as well as individual samples from different depths of water. The apparatus comprises a sampler (2) driven by an electric motor (3) and placed into connection with a buoyant container (10). The sampler is preferably a centrifugal pump (2) placed into connection with the container (10). The suction side of the pump (2) communicates with the sampling point and the pressure side communicates with a sample receiver. The sampler (2) is arranged to operate under control of a control unit (8) for taking samples of specific volume at specific intervals. The control unit (8) is placed inside said container (10). The electric motor (3) is powered by an accumulator (7) placed preferably inside the container (10).

The invention relates to an apparatus for water sampling. The inventionrelates to such a water sampling apparatus that permits intake ofso-called composite samples as well as individual samples from differentdepths. A composite sample denotes a sample which has been acquired bytaking a small water sample e.g. at one hour intervals for one day intoa sample receiver where the samples are mixed and wherefrom the actualwater sample is taken for the desired water analyses. Composite samplesare needed particularly in monitoring of the quality of natural watersand in monitoring and control of the operation of a water purificationplants.

The patent publication U.S. Pat No. 4,462,265 discloses a system whereina mechanical power unit lowered deep in the water is towed by a shipmoving on the surface, the unit having a pump to pump water up. Thewater flows through several collection devices placed in series atvarious depths between the unit and the ship. The pressure of this waterflow is adjusted by means of a throttle on the ship to a value highenough to actuate the valves of the collection devices and therebypermit the water samples in them to be conducted up to the ship. Thepump gets its driving power from the towing movement of the ship bymeans of a turbine. The water sampling apparatus is large and isintended for moving and manned sampling from great and deep watersystems.

Water samples are still collected so that the sample collecting persongoes to the monitoring site at certain intervals to take a small sampleinto the collecting container. Sampling itself does not generally takemuch time so that the sampling costs are primarily made up of wage andtravelling costs. Sampling devices operating on the piston principle areavailable. Since this kind of device needs a voltage of 220 V, it isdifficult to install in terrain circumstances. The device also comprisesa glass hoisting device which is heavy and breaks easily. The device isvery expensive and therefore its use has remained limited.

The patent publication U.S. Pat. No. 4,462,265 discloses a systemwherein a mechanical power unit lowered deep in the water is towed by aship moving on the surface, the unit having a pump to pump water up. Thewater flows through several collection devices placed in series atvarious depths between the unit and the ship. The pressure of this waterflow is adjusted by means of a throttle on the ship to a value highenough to actuate the valves of the collection devices and therebypermit the water samples in them to be conducted up to the ship. Thepump gets its driving power from the towing movement of the ship bymeans of a turbine. The water sampling apparatus is large and isintended for moving and manned sampling from great and deep watersystems.

The objective of the invention is to present an apparatus that allowsautomatic water sampling without the need for a continuous manning ofthe monitoring site. A further objective is a sampling apparatus whichis small and moderate-priced. These objectives are obtained by means ofan apparatus which is primarily characterized in what is presented inthe characterizing part of claim 1.

In the apparatus according to the invention the sampler is a pump whichis driven by an electric motor and which is placed into connection witha buoyant container. The apparatus is powered by an accumulator so thatelectric power lines are not needed at the sampling site as in the caseof prior art apparatuses. Because the apparatus is cheap on one hand andeasy to transport on the other hand, sampling apparatuses needed inseveral monitoring sites can be installed in one go and also the samplescan be collected in one go.

The invention will be described in greater detail in the followingreferring to the enclosed drawings in which

FIG. 1 shows a vertical cross-section of the apparatus and

FIG. 2 shows a horizontal cross-section of the apparatus.

The apparatus according to the invention consists of a buoyant samplingdevice 2 driven by an electric motor 3. In the exemplary case thesampling device 2 is a centrifugal pump which is mounted to a sealed,buoyant container 10. The container 10 is, in the exemplary case, madeof plastic. Pump 2 is placed so that its suction side communicates withthe sampling point and the pressure side communicates with the samplereceiver (not shown in the figures) e.g. by means of hoses. In theexemplary case, container 10 also accommodates other equipment which areneeded in the sampling operation.

The buoyancy of container 10 is accomplished by the vessel-like orcasing-like structure and the fact that the lower part of container 10is filled with a material like polystyrene, for example, which islighter than water. The walls of the container may also be provided withair-filled cavities. Container 10 has a tightly closing cover 11. Atubular part 12 in the middle of container 10 leading through the bottomof the container is welded to the bottom of container 10. The tubularpart 12 is placed so that its first end i.e. the upper end extendsapproximately to the middle of container 10 and its second end i.e. thelower end slightly below the bottom of container 10. Both ends of thetubular part 12 are open. The first end of the tubular part is providedwith threads 13.

The sampling device 2 is driven by a motor 3. In the exemplary case,motor 3 is fastened in position onto the first end of the tubular part12 by means of threads 13. Motor 3 is above the tubular part 12 and itcloses watertightly the first end of the tubular part 12 i.e the upperend.

Motor 3 and the sampling device 2 are placed into connection with thetubular part 12 so that the shaft 4 of motor 3 which drives pump 2 isinside the tubular part 12. The length of shaft 4 is such that pump 2 islocated slightly below the bottom of container 10 at the second end ofthe tubular part 12. When the apparatus is placed in position forsampling, the tubular part 12 becomes at least partly filled with water.Pump 2 is placed so that the water sample can be taken from a flowingwater right below the apparatus or from a desired depth by means of anextension tube connected to the suction opening of pump 2. Because inthe apparatus according to the invention the suction side of pump 2 isin continuously communicating with the water which is being sampled, noair can accumulate in the apparatus which would interfere with sampling.

A tube 5 leads from pump 2 to the sample receiver which can be aseparate watertight container which floats on water. The sample receivercan also be placed farther or higher from the actual sampling apparatus.

If it is desired to use the apparatus for sampling at greater depths, atube 6 can be attached to the suction opening of the pump wherebysamples can be collected from a desired depth below container 10. If theapparatus is used for collecting samples from various depths, tube 6 islowered to the desired depth and the first sample is extracted into thecontainer. Tube 6 is then lowered for a desired distance and the secondsample is extracted into the container in this case, the apparatus mustbe operated so that the water in the tube is first conducted past thecontainer before the actual water sample is taken from the desireddepth. When the samples have been collected, tube 6 is lifted manuallyor by a specific winch (not shown in figures).

The electric motor 3 driving pump 2 is powered by an accumulator.Accumulator 7 is placed inside container 10 to the bottom thereof.Accumulator 7 can be a 12 V battery generally used in battery-drivendrilling machines. Container 10 also accommodates a control unit 8, e.g.a timer, and a relay 9 for controlling the operation of the electricmotor 3 and pump 2. By means of timer 8, pump 2 can be programmed topump water at specific intervals and the length of the run time of pump2 can also be adjusted. Timer 8 is preferably of the kind that allowsstepless control. The length of the run time of pump 2 is adjusted to asuitable value depending on the volume of water needed and the power ofthe pump. For a composite sample only about 20 cl of water is needed foran individual sample at a time. It takes only 2-3 seconds to pump thisquantity of water.

The equipment needed for the control and driving of pump 2 can benaturally placed also outside the apparatus. This can be doneparticularly in the case when the intention is to vary the sample volumeor the sampling rate during the collection operation.

In addition to composite samples the apparatus enables collection ofso-called undisturbed individual samples from different water depths.Samples can be taken in vertical direction at arbitrary depths bylowering the tube connected to the suction side of the pump. By means ofthe apparatus it is possible to localize accurately in verticaldirection e.g. water layers with low oxygen content and observe invertical direction other changes which affect the water quality. Forexample, the apparatus greatly facilitates following of narrow wastewater zones which move underwater.

The invention is not limited to the above embodiments but it can bevaried within the limits of the enclosed claims. Therefore, the samplercan also be a membrane pump or a peristaltic pump.

I claim:
 1. A buoyant apparatus for water sampling comprising:(a)buoyant container (10) capable of being closed watertightly; (b) in saidcontainer, an electric motor (3) and a battery (7) for supplying powerto said electric motor; (c) a pump (2) mounted to said container anddriven by said electric motor, said pump having a suction side and apressure side; (d) connected to the suction side of said pump, means (6)for communicating with a sampling point; (e) connected to the pressureside of said pump, means (5) for communicating with a sample receiver;and (f) in the container, a control unit (8) controlling the operationof said electric motor;wherein said control unit (8) is programmable torun said electric motor (3) and pump (2) during certain run times atspecific intervals for taking samples.
 2. Apparatus according to claim1, wherein the pump (2) is a centrifugal pump.
 3. Apparatus according toclaim 1, wherein the pump (2) is placed inside a tubular part (12) whichopens to the bottom of the container (10).
 4. Apparatus according toclaim 1, wherein the electric motor (3) is attached to the upper part ofthe tubular part (12) and the pump (2) is mounted on the shaft of theelectric motor (3) inside the tubular part (12).
 5. Apparatus accordingto claim 1, wherein the means communicating with the sampling pointincludes a tube (6) the mouth of which can be lowered to a desired depthfor taking a water sample.